tree 874b10fc11da3178e4630f7a430e1b299d3b3806
parent 00e23707442a75b404392cef1405ab4fd498de6b
author David Howells <dhowells@redhat.com> 1539993476 +0100
committer David Howells <dhowells@redhat.com> 1540338067 +0100

iov_iter: Separate type from direction and use accessor functions

In the iov_iter struct, separate the iterator type from the iterator
direction and use accessor functions to access them in most places.

Convert a bunch of places to use switch-statements to access them rather
then chains of bitwise-AND statements.  This makes it easier to add further
iterator types.  Also, this can be more efficient as to implement a switch
of small contiguous integers, the compiler can use ~50% fewer compare
instructions than it has to use bitwise-and instructions.

Further, cease passing the iterator type into the iterator setup function.
The iterator function can set that itself.  Only the direction is required.

Signed-off-by: David Howells <dhowells@redhat.com>